CHEMICALLY VAPOR-DEPOSITED DIAMOND FILMS GROWN ON TITANIUM NITRIDE COATED AND UNCOATED IRON SUBSTRATES

The nature of the interfaces of chemically vapor deposited diamond fil ms on Fe substrates with and without a protective TiN coating is inves tigated. For unprotected Fe substrates a thick graphitic soot containi ng 6.5% Fe grows upon the Fe in the first few minutes of exposure to t he plasma and, once this soot completely covers the substrate, diamond can nucleate and grow upon it into an average quality unfaceted conti nuous diamond film. However, adhesion is poor, the weak link being the lack of structural integrity of the soot layer itself. A TiN coating is found to prevent soot formation, C diffusion into the Fe bulk, and Fe diffusion into the diamond films. In the initial stages of growth t he TiN is covered with a thin layer of amorphous carbon (a-C), and it is on this layer that diamond nucleates and grows. Here, again, adhesi on is not strong, with delamination occurring at the TiN/a-C interface .